Mindfulness DOI 10.1007/s12671-013-0234-6
ORIGINAL PAPER
One-Session Mindfulness Meditation: A Randomized Controlled Study of Effects on Cognition and Mood Susan Johnson & Ravid Moses Gur & Zhanna David & Elise Currier
# Springer Science+Business Media New York 2013
Abstract Participants in previous studies of brief mindfulness meditation (MM) are often tested immediately following a meditation session, making it difficult to separate several days of training from one-session effects. The current study examined the effects of a single session of 25 min of MM compared with a sham meditation (sham M) and a booklistening control. One session of both MM and sham M had a significant effect on state mindfulness compared with the control. Several mood subscales as well as total distress score on the Profile of Mood States (POMS) were also significantly different from control. However, neither meditation condition had significant effects on any of the attention and working memory tasks. These results indicate that one session of meditation was not sufficient to affect the cognitive tasks used in this study. Both MM and sham M positively affected mood states and heightened state mindfulness. Keywords Mindfulness . Meditation . Decentering . Mood . Attention
Introduction Brief mindfulness exercises have been found to affect state mindfulness, pain levels, cognitive performance, and mood. It is important to understand more clearly the effects of brief and single sessions of meditation. Studies of brief mindfulness meditation (MM) on mood and cognition vary in length and intensity of meditation training. At a more basic level, S. Johnson (*) : R. M. Gur : Z. David Department of Psychology, University of North Carolina at Charlotte, Charlotte, NC 28223, USA e-mail:
[email protected] E. Currier Department of Biology, University of Miami, Coral Gables, FL 33143, USA
studies vary in whether participants are tested immediately following a meditation session or at some later time. Such variability may lead to conflating of state effects of a meditation session with effects from several days of sequential practice. The dose effect of these brief meditation formats is largely undetermined. Furthermore, some studies of the effects of one session of meditation have found positive effects on mood (Feldman et al. 2010; Erisman and Roemer 2010; Thompson and Waltz 2007; Zeidan et al. 2013) and cognition (Mrazek et al. 2012) and these findings require further investigation. In the current study, we compare the effects of one session using measures that have been found effective for 3 or 4 days of brief MM. Brief meditation formats of three to five sessions have been found to improve mood, cognitive performance on some tasks, and reduce pain reports. Three days of MM was found to be effective at reducing negative mood, depression, fatigue, confusion measured by the Profile of Mood States (POMS) scale, as well as reducing heart rate (Zeidan et al. 2010c) compared with sham and control conditions. In another study, 3 days of training was effective at reducing pain ratings and sensitivity, as well as anxiety scores when compared with baseline and other cognitive manipulations (Zeidan et al. 2010a). In a study examining the effects of instructor-guided MM training (4 days 30 min−1 day−1) compared with booklistening controls on cognitive tasks (Zeidan et al. 2010b), both conditions were effective at improving mood but only brief MM training reduced fatigue, anxiety, and increased mindfulness. Moreover, brief MM training significantly improved performance on tasks measuring visual-spatial processing, working memory, and executive functioning compared with the control group. A four-session study compared the effects of a mindfulness intervention to no intervention on mood and anxiety vulnerability in an Israeli community sample (Tanay et al. 2012). The intervention conducted was 60-min instructorguided mindfulness training that took place four times over
Mindfulness
the course of 21 days. Emotions and mood were measured using self reports administered after weekly interventions as well as pre- and post-intervention assessments. Participants were asked to complete the battery of self reports within 48 h of their final session. Subjects in the intervention group showed improved mood and reduced anxiety vulnerability as measured by the Positive and Negative Affect Schedule (PANAS), Anxiety Sensitivity Index (ASI) and Dysfunctional Attitudes Scale-Revised (DAS-R) (Tanay et al. 2012). Tang et al. (2007) found that five training sessions on integrative body–mind training intervention was effective in improving cognitive functioning and in decreasing negative mood and stress-related cortisol levels in Chinese undergraduates. Participants were randomized into either a control group participating in relaxation training or an experimental group participating in integrative body–mind training (IMBT). The intervention which included MM training was given over 5 days for 20 min/day. Attention tests and self reports were given 1 week before the intervention and immediately following the final session on day 5. Participants in the experimental group showed a significant decrease in anxiety, depression, anger and fatigue and an increase in vigor as measured by POMS (Tang et al. 2007). On the Attention Network Test (ANT), the IMBT group showed significantly higher scores on the Conflict task on the ANT indicating improvements in the efficiency of executive attention. These studies illustrate that brief MM interventions can have immediate beneficial effects on a variety of outcomes. In the studies cited above, the brief mindfulness intervention took place over sequential days and the participants were tested at the end of session on their last day (with the exception of Tanay et al. 2012). In the current study, we wanted to rule out the possibility that these are session effects. That is, do participants see benefits because they participated in 3, 4, or 5 days of MM or can we see the same effects after just one session? Since in the previous designs participants were tested shortly following their last MM session, we cannot rule out a session effect. The goal of the present study was to investigate whether there are dose effects for MM by using same measures that were shown to be sensitive to 3- and 4-day brief meditation training (Zeidan et al. 2010b; Zeidan et al. 2010c). There are also studies that have investigated the effects of a single session of meditation and measure mindfulness, mood, and cognitive performance. Thompson and Waltz (2007) found that trait mindfulness is not necessarily predictive of state mindfulness in an undergraduate sample naïve to meditation. Although state versus trait mindfulness was the focus of the study, they employed one session of meditation and measured mood on the PANAS before and after the meditation exercise. Thompson and Waltz (2007) ran groups of 15 undergraduates at a time. They were instructed to face their chairs toward a blank wall, follow the flow of their breath for 15 min, and bring their attention back to the breath
if they were distracted. They found that both positive affect and negative affect decreased after the meditation session. Feldman et al. (2010) compared the immediate effects of 15 min of either mindful breathing (MB), progressive muscle relaxation (PMR), or loving-kindness meditation (LKM) in female undergraduates to test whether decentering is unique to MM or common across approaches. Decentering involves viewing internal experiences in an objective way, separating yourself from your thoughts to reduce emotional reactivity. The MB exercise consisted of listening to a 15-min audio recording which included 12 min of guided instruction followed by 3 min of silence. Participants were guided to become aware of sensations, especially those of breathing, to notice when their minds wander and to nonjudgmentally bring their focus back to the breathing. All three groups reported significantly lower negative effect on the PANAS post-session. Participants completed measures of decentering, frequency of repetitive thoughts (RT) experienced during the exercise, and degree of negative reaction to thoughts. Participants in the MB condition reported greater decentering relative to the other two conditions. Additionally, the association between frequency of RT and negative reactions to thoughts was relatively weaker in the MB condition than in the PMR and LKM conditions, in which these two variables were strongly and positively correlated. Feldman et al. (2010) suggest that MB is related to higher levels of decentering, while other elements of MBSR such as PMR or a loving kindness exercise did not lead to such improvements. Frewen et al. (2011) measured the immediate response to mindfulness mediation exercises of 10 and 15 min in undergraduate nonmeditators. The participants sat in a classroom and were given in-person instructions to breathe nasally and diaphragmatically while maintaining attention on the flow of the breath. Participants were instructed that when they became aware of the wandering of their attention they should gently and nonjudgmentally “let go” of the distraction and return their attention to breathing. They asked participants to report their “meditation breath attention scores” (MBAS) by querying them at intervals during the exercise whether their attention was directed towards their breathing or whether their mind had wandered. The purpose of the studies was to explore the psychometrics of the MBAS. Surprisingly, the MBAS was not correlated with Decentering on the state Toronto Mindfulness Scale in either 10 or 15 min sessions of MB. The 15-min MB exercise found that MBAS was inversely associated with the degree of self-reported mind wandering and positively correlated with the Five-Factor Mindfulness Questionnaire scale of “Acting with Awareness”. Mrazek et al. (2012) investigated mindfulness as non distraction as it is operationalized by the MAAS. They hypothesize that mindfulness entails a capacity to avoid distraction and sustain attentiveness, and thus is the conceptual opposite
Mindfulness
of mind wandering. In an 8-min MB condition, participants were provided with written instructions to sit upright while focusing attention on the sensations of the breath and to return their attention to the breath when distracted. Mrazek et al. (2012) found MB improved Sustained Attention to Response Task (SART) performance relative to passive relaxation or reading comparison groups. Erisman and Roemer (2010) measured the effects of a 10min mindfulness exercise on positive and negative affective experiences caused by emotionally evocative film excerpts. Participants were randomized into either a mindfulness or a control group. The mindfulness group listened to audiotaped information about mindfulness, a breath awareness exercise, then they heard about the application of mindfulness to emotional experiences and were guided through an experiential exercise practicing mindfulness of emotions. The three film excerpts were each aimed to evoke a different emotion; distress, amusement, and one that was affectively mixed. Emotions were measured before, in between, and after the films using self reports. Participants in the mindfulness group showed higher positive effect in response to the amusing film, and lower negative effect to the mixed film relative to controls. There were no differences between the groups in response to the distressing film clip (Erisman and Roemer 2010). A one-session study has also been shown to reduce physiological measures of stress. Mohan et al. (2011) used a challenging computer game to induce stress in Indian male students naïve to meditation. They compared a group that waited quietly after the stressor compared with a group listening to an audio-guided 20-min meditation session composed of breath concentration instructions followed by suggestions of “peace, stillness, and thoughtlessness.” The meditation group displayed significant decreases on Galvanic Skin Response, EMG QTc/QS2 ratio (an index of sympathetic discharge to the heart). This indicated that meditation reduces sympathetic nervous system responses to stress more effectively than just sitting quietly. The studies cited above indicate that single sessions of mindfulness can affect state mindfulness, emotion, stress physiology, mood, and cognitive performance. Importantly, all of the previous one-session studies employed very similar techniques that emphasized MB techniques. The goal of the current study was to examine effects of one session of MM using a three armed randomized controlled design. One arm included a sham M session to see if any outcomes are due to expectancy effects. Participants were administered selfreport scales of state mindfulness, mood, depression, anxiety, as well as standardized and experimental tests of focused attention and working memory. Mood measures that have been shown to be sensitive in a 3-day MM exercise (Zeidan et al. 2010c) as well as standardized and experimental measures of cognitive domains that have been shown to be
sensitive to a 4-day MM intervention (Zeidan et al. 2010b) were administered. The current study tested all participants immediately after just one session of MM or one session of book listening. Based on prior one-session studies, the hypotheses for the current study were that one session of MM will improve state mood more effectively than book listening. One session of mindfulness has been shown to improve on POMS subscales (Zeidan et al. 2010c) and on PANAS mood measures (Feldman et al. 2010; Thompson and Waltz 2007). Secondly, it was hypothesized that one session of MM will improve state anxiety as has been found in several prior studies (Zeidan et al. 2010c; Zeidan et al. 2013). The sham M may also have positive effects on mood but there are no previous single-session studies that have employed a sham M, so these analyses are exploratory in nature. The analyses of the effects of one-session MM versus sham and book listening control on the cognitive tasks, state mindfulness, and RT were exploratory in nature. There is no sufficient literature on the specific measures used in the current study and one-session mindfulness exercises to make predictions. A manipulation check was used to assess the perceived validity of the MM and sham Ms.
Method Participants Students from a large Southeastern university participated in exchange for course credit. The participants were recruited via the University subject pool. The recruitment script requested students who were interested in learning meditation but had no prior meditation experience. The protocol was approved by the University Institutional Review Board. A total of 92 participants completed the protocol. The sample was 65 % female, and the mean age of the participants was 23.4 ± 8.2 years (range, 18–57). In ethnic composition, 56.5 % of the participants self-identified as White, 25 % as African-American, 8.7 % as Hispanic, 6.5 % as Asian, and 3.3 % as biracial, Native American, or Other. Self-Reported Measures Repetitive Thoughts Questionnaire (RTQ; Feldman et al. 2010)—participants were asked to report on their experiences during the exercise. The RTQ has a two-factor structure with five items assessing frequency of RT (e.g., thoughts about one or more problems in your life, a mental to-do list, and criticisms of yourself) scored from 0 (never) to 4 (almost constantly.) The second factor consists of three items assessing negative reactions to thoughts (e.g., to what degree were you upset, annoyed, or distracted by thoughts) scored from 0 (slightly or not at all) to 4 (extremely). Alpha
Mindfulness
reliability for frequency of RT was 0.83, and for negative reaction to RT was 0.81 in this sample. Toronto Mindfulness Scale, state version (TMS; Lau et al. 2006) has 13 items and a two-factor structure (curiosity and decentering) that has been validated in a number of clinical contexts (Davis et al. 2009). The items of factor 1 (curiosity) reflect an attitude of wanting to learn more about one’s experiences (e.g., “I was curious about each of the thoughts and feelings I was having”). The items of factor 2 (decentering) reflect a shift from identifying personally with thoughts and feelings to relating to one’s experience in a wider field of awareness (e.g., “I was aware of my thoughts and feelings without over-identifying with them”). Items are scored from 0 (not at all) to 4 (very much). Higher scores indicate higher levels of mindfulness in response to the exercise. Coefficient alpha for the curiosity and decentering subscales in this sample were 0.90 and 0.78, respectively. State-Trait Anxiety Inventory, Form Y-state version (Spielberger 1983) comprises 20 statements to be rated on a 4-point scale (1=almost never; 4=almost always). The participants rate the statements based on how they feel at the moment. Sample items are: “I lack self confidence,” “I feel nervous and restless,” and “I am ‘calm, cool, and collected.” In this sample, the alpha coefficient was 0.94. POMS is a 65-item adjective checklist designed to assess current affective states on a 5-point scale (1=not at all; 5= extremely). The measure provides a Total Mood Disturbance score and 6 subscales of mood (i.e., tension, depression, and anger, confusion, vigor, and fatigue) (McNair et al. 1971). In this sample, the alpha coefficient for tension was 0.85, for depression 0.87, for anger 0.94, for vigor 0.88, for fatigue 0.89, and for confusion 0.83. Manipulation check—the MM and sham M participants circled a number from 1 (not at all) to 10 (very much so) indicating how much they felt that they were truly meditating during the exercise. Cognition Tasks The cognitive tasks were administered to each participant individually. Symbol Digit Modalities Test (SDMT; Smith 1982), paper version, was used to assess working memory and attention that is necessary for complex scanning and visual tracking (Shum et al. 1990). SDMT requires decoding of a series of numbers listed on paper according to a corresponding template of visual symbols. The dependent measure is the number of correctly paired responses in 90 s. Computer-adaptive adjustable two-back task is an accuracy selectable, two-back task that consists of 54 trials and was developed in order to measure information processing speed, working memory, and attention. It represents an advance over previously used n-back tasks (as cited in Strauss
et al. 2006) because it corrects for the accuracy-speed confound by allowing the experimenter to set desired accuracy levels and by equating accuracy levels across groups. The program’s algorithms variably adjust the presentation speed based on individual trial responses, response patterns, and multiple accuracy windows to a value that supports the desired accuracy. Participants view a sequence of letters and indicate whether or not a probe letter is the “same” or “different” as the stimulus item presented two items back. Research has provided evidence of face, concurrent, and predictive validity (Diamond et al. 2008); Lengenfelder et al. 2006; Zeidan et al. 2010b). The program computes two measures: speed of processing and extended hit rate (representing a run of correct responses). A measure of accuracy of 0.70 was required for all participants so that accuracy level was controlled for. Forward/backward Digit Span subtests of the Wechsler Adult Intelligence Scale-IV (Wechsler 2008) were used to measure immediate memory span. The dependent measure was the sum of the scores for total forward digit span and total backward digit span. In the forward digit span, subjects can correctly repeat back a span of up to 16 digits. In the backward version, subjects can recite back a span of up to 14 digits backwards. Higher scores are indicative of higher memory recall. Digit span backward also requires executive attention. Trail Making Test, parts A and B (Reitan 1958) are visual tracking and attentional set shifting tasks. In trails A, the examinee draws a line to connect the numbers 1 through 25 in order. Each numeral is contained in a plain circle. Any errors are corrected and the examinee continues. Their score is the amount of time elapsed in seconds. In trails B, the examinee draws a line to connect in alternating sequence the numbers 1 through 13 and the letters A through L. The examinee begins with 1 and then draws a line to A, then proceeds to 2, then B, and so on until all the numbers and letters are connected. Again, any errors are corrected and the examinee continues. Trails B places greater demands on motor speed and visual attention than trails A. The score for both tasks is the amount of time elapsed in seconds. Lower scores indicate better performance. Procedure Sessions were scheduled for early or mid-afternoon and participants were run in groups of two or three people. Randomization occurred just before participants arrived using a computerized random numbers program. After giving informed consent, participants were seated in a circle and listened for 25 min to either MM, sham M, or book on CD. A research assistant sat with the participants to supervise the session. After listening, participants completed the selfreported measures and were administered the cognitive tasks
Mindfulness
in random order. The entire session took approximately 90 min. All participants were debriefed at the end of the session. Randomization resulted in 41 participants in the MM group, 25 in the sham M group, and 26 in the book listening control group. There were no differences between the groups on age F(2, 89)=0.63, p=0.53, gender distribution χ2 (2)=0.26, p=0.87, or ethnic composition (distribution of White versus non-White) χ2 (2)=1.1, p=0.58. The meditation and the sham M CDs were created by Fadel Zeidan using the similar instructions to those used for the first day of the brief (3 and 4) day intervention studies cited above. The verbatim scripts of MM and sham M exercises can be viewed in Appendix A. The main difference between the MM and the sham M was in a greater level of detail on breathing instructions and the greater emphasis on acceptance of thoughts on the MM CD relative to the sham M. The sham group had longer periods of silence was not given the guided instruction of focusing on the flow of the breath imperative for concentrative meditation. In the MM and sham groups, the RA followed the instructions and engaged in the exercise with the participants. Book Listening Control The purpose of the book listening group was to compare the mindfulness and sham M groups to a non-manipulated group that met for the same time period, in the same setting, while their attention was occupied by a narrated story. Control group participants also believed that they were registering for a mindfulness intervention. Control participants were instructed to listen to JRR Tolkein’s The Hobbit on compact disc (BBC audiobooks Ltd, 1997). The beginning of the first chapter “An Unexpected Party” was played. Participants were instructed to silence cell phones and any electronics, sit quietly and listen to the audio book. A research assistant sat with the participants to monitor attentiveness during the listening task. Statistical Analysis Overall multivariate analysis of variance (MANOVA) analyses with post hoc comparisons was performed for the POMS subscales. If the overall MANOVA was significant, Tukey’s HSD post hoc comparisons were run to examine differences within groups. Separate univariate ANOVAs were run for the cognitive tasks, mindfulness, SAI, RT, and the manipulation check. Partial Eta squared effect size statistics are reported for all of the univariate analyses. Pearson’s R correlations were performed examine associations between negative reaction to RT during MM, sham M, and book listening. To determine if correlation coefficients are significantly different between groups we used the Preacher (2002) calculation of z-score
using Fisher’s r-to-z transformation. All statistics were computed using SPSS version 19.0.
Results An ANOVA found no significant difference on the manipulation check F(1, 62)=1.09, p=0.30, ηp2 =0.017. The MM groups scored an average of 6.4±1.6 while the sham scored an average of 5.8±2.5. This suggests that the sham was not perceived as significantly different from the actual MM. There was a significant difference among the three groups on the TMS scales of curiosity F(2, 88)=5.45, p=0.006, ηp2 =0.111 and decentering F(2, 88)=4.167, p=0.019, ηp2 =0.087. Post hoc analysis using Tukey’s HSD showed that both the MM group (p=0.008) and the sham M group (p=0.02) were significantly higher on TMS curiosity compared with the book group. Only the MM group was significantly higher on TMS decentering compared with the book group (p=0.02). There were no differences between MM and sham M on the TMS scales. There were no significant differences between groups on SAI F(2, 88)=2.36, p=0.100, ηp2 =0.052; RT frequency F(2, 88)=0.415, p=0.662, ηp2 =0.010; or RT-negative reactions F(2, 88)=0.511, p=0.602, ηp2 =0.012. Descriptive statistics for these self report scales are presented in Table 1. The overall MANOVA for all of the POMS subscales was significant F (2, 88) 1.8, p=0.05. Post hoc analysis using Tukey’ HSD found significant differences from controls on the tension, anger, fatigue, confusion, and total scores (see Fig. 1). Specifically, on the tension, confusion and total POMS distress score both MM and sham M groups scored significantly lower than the control group. On the anger and fatigue subscales, only the sham group scored significantly lower than controls. The MM and sham groups were not significantly different from each other on any POMs measures. Univariate ANOVAs found Tension F(2, 89)=4.66, p=0.012, ηp2 =0.098; depression F(2, 89) = 2.27, p = 0.109, ηp2 = 0.050; anger F(2,89)=3.20, p=0.046, ηp2 =0.069; vigor F(2, 89)=0.393, p = 0.676, ηp2 = 0.009; fatigue F(2, 89) = 4.19, p = 0.018, ηp2 =0.089; confusion F(2, 89)=4.406, p=0.015, ηp2 =0.093; and total distress F(2, 89)=3.54, p=0.033, ηp2 =0.076. Univariate analyses were run for the each of the cognitive measures. There were no significant differences on any of the measures between groups, trails A, F(2, 89)=2.6, p=0.086, ηp2 =0.054; trails B, F(2, 89)=1.16, p=0.32, ηp2 =0.025; SDMT, F(2, 88)=0.357, p=0.701, ηp2 =0.008; Digit Span Forward F(2, 89)=0.468, p=0.628, ηp2 =0.010; Digit Span Backward F(2, 89)=0.213, p=0.808, ηp2 =0.005; and extended hit rate F(2,86)=0.139, p=0.870, ηp2 =0.003 (see Table 2 for descriptive statistics). Pearson correlation coefficients found frequency of RT was strongly associated with negative reactions to thoughts. When MM, sham M, and book were collapsed, there was large
Mindfulness Table 1 Descriptive statistics for self-reported measures MM (M (SD))
Sham Control (M (SD)) (M (SD))
SAI 32.9 (11.3) 32.1 (8.1) 38.3 (12.9) Repetitive thought 7.9 (4.7) 6.9 (3.7) 7.3 (5.2) frequency Repetitive thought 3.6 (2.5) 3.2 (2.2) 3.9 (3.2) negative affect TMS decentering 14.4 (5.4) 14.1 (5.5) 10.8 (5.0)* TMS curiosity 13.5 (6.7) 13.4 (5.2) 8.8 (5.3)**
Table 2 Descriptive statistics for cognitive measures mean (SD) F
p
2.3 0.10 0.41 0.66 0.51 0.60 4.1 5.4
0.019 0.006
SDMT EHR Digit span-front Digit span-back Trails A Trails B
MM
Sham
Control
59.2 (8.09) 2.5 (3.3) 10.6 (2.3) 7.8 (2.0) 25.4 (7.7) 59.6 (18.6)
58.5 (11.9) 2.9 (3.4) 10.8 (2.1) 8.08 (1.7) 27.8 (8.8) 61.3 (20.5)
60.7 (7.8) 2.3 (2.9) 11.1 (1.9) 8.3 (2.3) 23.1 (6.6) 54.7 (16.0)
SDMT Symbol Digit Modalities Test, EHR extended hit rate *p
